JavaScript 求解某日期为一年中的第几周.doc

JavaScript 求解某日期为一年中的第几周 导读：就爱阅读网友为您分享以下“JavaScript 求解某日期为一年中的第几周”的资讯，希望对您有所帮助，感谢您对92的支持! 来源：Oracle里有select to_char(to_date(#39;2013-03-18#39;,#39;yyyy-MM-dd#39;),#39;iw#39;) from dual;可求某日期属于第几周（ISO 周），今用JavaScript实现之（包括它的逆运算）本算法参考ISO周的维基百科：/wiki/ISO_week_date测试环境：win7+Chrome24.0lt;script language=quot;javascriptquot;gt; // Calculating the week number of a given datefunction getWeek(date){var result=null;var array=[0,31,59,90,120,151,181,212,243,273,304,334];var month=date.getMonth();var weekday= date.getDay()==0?7:date.getDay();var year=date.getFullYear();var tmp=array[month]+date.getDate()+10-weekday;if(monthgt;1amp;amp;isLeapYear(year)){tmp++;}//If the week number thus obtained equals 0, it means that the given //date belongs to the preceding (week-based) year. If a week number //of 53 is obtained, one must check that the date is not actually//in week 1 of the following year.if(tmplt;7){if(isLeapYear(year-1)){result=parseInt((tmp+366)/7);}else{result=parseInt((tmp+365)/7);}}else{result=parseInt(tmp/7);if(53==result){result=checkIs53thWeek(date)?53:1;}}return result;}/*** Number of ISO weeks in an ISO year* The 53-week ISO week-numbering years can be described by any of the following equivalent definitions:* years with the dominical letter ED, D, or DC;* all years starting on Thursday, and leap years starting on Wednesday;* all years ending on Thursday, and leap years ending on Friday;* years in which either 1 January or 31 December is a Thursday (in leap years), or in which both are Thursdays (in common years).* All other week-numbering years have 52 weeks.*/function checkIs53thWeek(date){//Years in which either 1 January or 31 December is a Thursday (in leap years), or in which both are Thursdays (in common years).var jan1=new Date(date.getFullYear(),0,1);var dec31=new Date(date.getFullYear(),11,31);if(jan1.getDay()==4||dec31.getDay()==4){return true;}return false;}function isLeapYear(year){return ( year%4 == 0 ) amp;amp; (( year%100 != 0 ) || ( year%40